Method of and apparatus for operating hot cathode lamps



July 22, 1947.

METHOD OF AND B. P. RUPERSBURG APPARATUS FOR OPERATING HOT CATHODE LAMPS Filed Ju1y'31, 1944 D 2 WM-I} GI 2 I A B 2 0' l T I I] T3 6' INVENTOR. BURGHARDT R RUPERSBURG BY AM d M AITORNEYS Patented July 22, 1947 METHOD OF AND APPARATUS FOR OEERATING HOT CATHQDE'LAMPS Burghardt P. Rupersburg, St. Clair Shores, Mich,

assignor, by mesne assignments, to Syncro Devices, Inc., Detroit, Mich, a corporation of Michigan Application July 31, 1944, Serial No. 547,329

Claims.

The invention relates to an improved circuit for operating hot cathode, gas or vapor lamps.

In the present state of the art, hot cathode lamps in commercial operation require the use of a separate transformer and also thermostatically operated switches connected into the circuit between the transformer and lamps. These elements not only add to the cost of the original installation, but also introduce certain maintenance problems because of the mechanically operating parts.

It is an object of the present invention to provide a circuit control for hot cathodelamps which is entirely electrical and free from mechanically operated parts.

Anotherobject is to provide a circuit for hot cathode lamps which obtains instant starting and uniform operation when the lamps are connected to ordinary commercial power lines such as 120 volts, 6 0 cycle A. C.

These and other objects are attained by providing the apparatus hereinafter more fully described and illustrated in the accompanying drawings, wherein Figure 1 is a circuit diagram illustrating my invention as applied for operating a pair of hot cathode lamps;

Figure 2 is a circuit diagram illustrating the invention as applied for operating a single hot cathode lamp.

In the drawings, A represents a commercial typeof hot cathode gas discharge lamp comprising an elongated transparent tube B filled with suitable gases or vapors in the known manner and having cathodes D and D at opposite ends thereof. These cathodes are in the form of filaments each connected to two terminals F1, F2, F3 and F4 respectively. The cathodes are usually connected to the protective horns G1 and G2 in the known manner.

Referring now to the circuit for the single lamp illustrated in Figure 2, the terminal F1 is connected to one side of the line through capacitance C1 and inductance L1. The terminal F3 at the opposite end of the lamp is connected to the opposite side of the line. Terminals F2 and F4 are connected together through the inductance L2. The values for L1 and C1 are so selected as to be resonant at line frequency. The values of L2 and C1 must be partially resonant, sufficient to start the lamp in operation. Although not absolutely essential, it is preferable to place a small capacitance C3 across the line between L1 and G1 which has the efi'ect of increasing the ease of starting.

In Figure 1 a second lamp A1 having terminals T1, T2, T3 and T4 is connected toth-e circuit of Figure 1 in the following manner. Terminal T1 is connected through capacitance C2 to the line between L1 and C1. Terminal T3 is connected to the other side of the line. Terminals T2 and T4 are connected together through inductance Lc.

The values of the inductances and capacitances are predetermined to obtain the effect heretofore mentioned, namely, that L1 and C1 are near resonance at line frequency and L2 and C1 are partially resonant sufficient to strike. Without limitation, and merely by way of example, the following values for inductances and capacitances are given for the circuit of Figure 2 when operating on a cycle circuit.

L1 0.78 henrys, 20 ohms, 900 turns #26 American Wire Gauge, enameled copper magnet wire on an E1 #11 core, square stack. Butt joint assembly. Air gap 0.15 to .020.

L2 and L3 19.0 henrys, ohms D. C., 1200 turns #30 .American Wire Gauge, enameled copper magnet wire on an EI #625 core, square stack. interleaved. a I

01 and C2-4.0 to 4.75 microfarads.

Thevalues'for inductances and capacitances for the circuit of Figure 1 when operating on a 60 cycle circuit are the same as those given above for the circuit of Figure 2 except that in Figure 1 L1 is 1.50 henrys.

In each ofthe circuits of Figures 1 and 2 the principles of, resonance enter into the operation,.the wave forms are not distorted, nor are they exponential as one would expect from the use of large capacitances, nearly the opposite being true, resulting in increased lamp life, instant starting, even at low temperatures.

The absence of mechanical or thermal action insures long life, decreased maintenance, and higher efiiciency power transfer of this type of lamp auxiliary.

In explanation of operation of this type of circuit, L1 and C1 in Figure 2 are so adjusted that they are near resonance at line frequency. This allows nearly the full line voltage to appear at the lamp terminals, but a limited current flow which is primarily determined by the value of capacitance C1.

The energy appearing on the lamp side of C1 must pass through the inductance L2 which is so adjusted that it creates a slight rise in voltage acting in conjunction with 01. This rise in voltage plus the increased cathode temperature, which is due to the passage of current through the cathode, causes the lamp to strike a discharge. Immediately the lamp discharges, it

destroys the greater part of the resonant efi'ect between L2 and C1 allowing the lamp to pass the controlled current from the Li-Ci combination, the inductance L2 in effect dropping out of circuit due to its high impedance in relation to the negative resistance characteristics of discharge lamps L2 being a load controlled inductance immediately on slight reductions of line voltage cuts in the circuit to maintain the correct voltage for lamp operation, at the same time starting a current flowing through the lamp filaments raising their temperature, which allows the lamp to remain operating even at great reductions in the line voltage. When the line voltage resumes its normal value, L2 again drops out of circuit and the current ceases to flow through the filaments allowing the lamp to again function normally.

What I claim as my invention is:

1. A circuit for operating a plurality of hot cathode discharge lamps each of the type comprising a vitreous tube having two terminals at each end thereof and a cathode resistance within each end of the tube connected between the terminals at the respective ends of the tube, said circuit comprising an inductance and a capacitance connected in series with one of the terminals at each end of one of said tubes and a parallel connection connecting said inductance in series with a second capacitance and one of the terminals at each end of a second tube, the other terminals of each of said lamps being connected to a separate inductance for each lamp.

2. A circuit for a hot cathode discharge lamp comprisin a source of alternating current of predetermined frequency, a conductor between one side of said source and one end of a cathode resistance, a conductor between the other side of said source and one end of a second cathode resistance at the opposite end of said lamp thus completing a circuit through said lamp when the gas therein is ionized, an inductance and a capacitance in series in said circuit through said lamp having values such as to provide substantial resonance at said. predetermined frequency,;anda;second inductance connected between the other ends of said cathode resistances having a value'such'as to energize said cathodes sufficiently to ionize said gas to the striking point and to pass a substantial current through said lamp, said second inductance having a substantial-ly greater impedance than said first inductance;

3. A method of starting and maintaining a hot cathode discharge lamp without mechanically moving parts which comprises connecting said lamp to an alternatin current supply in series with an inductance and a capacitance and providing a second inductance of substantially greater impedance than said first inductance in a shunt circuit around said lamp including the cathode resistances in series with said second inductance.

4. The method of starting and maintaining a hot cathode discharge lamp which comprises passing an alternating current through an inductance and a capacitance in substantial resonance with the frequency, passing said current through the cathode resistances of said lamp and through a second inductance shunted around said lamp and having such value as to cause the lamp to strike and to thereafter pass the current between the cathodes of said lamp, said second inductance having a substantially greater impedance than said first inductance.

5. The combination with a hot cathode discharge lamp having cathode resistances at opposite ends thereof, of a source of alternating current supply of approximately 120 volts and 60 cycles, an inductance and a capacitance connected in series between said alternating current supply and said lamp, said inductance having an impedance on the order of 1.0 henry and said capacitance having a, capacity on the order of 4 microfarads, and a second inductance having an impedance on the order of 19.0 henrys connected between said opposite cathode resist-' ances and in series therewith, and in parallel with said lamp during both starting and operation of said lamp.

BURGHARDT P. RUPERSBURG.

REFERENCES creep The following references are of record in the of this patent:

UNITE?) STATES PATENTS Aug. 22, 1939 

